High intake of saturated fatty acids may increase risk of coronary heart disease

An analysis of two cohort studies found that high dietary intake of major saturated fatty acids was associated with an increased risk of coronary heart disease in adults who had no chronic diseases at baseline.

The saturated fatty acids were lauric acid, myristic acid, palmitic acid and stearic acid.

Lead researcher Geng Zong, PhD, of the Harvard T.H. Chan School of Public Health in Boston, and colleagues published their results online Nov. 23 in The BMJ.

“This study dispels the notion that ‘butter is back,’” Frank Hu, MD, PhD, a study co-author, said in a news release. “Individual saturated fatty acids share the same food sources, such as red meat, dairy, butter, lard and palm oil. Therefore it is impractical to differentiate the types of saturated fatty acids in making dietary recommendations, an idea that some researchers have put forth. Instead, it is healthier to replace these fatty acids with unsaturated fats from vegetable oils, nuts, seeds and seafood as well as high quality carbohydrates.”

Dietary guidelines suggest keeping saturated fatty acid intake below 10 percent of total energy, according to the researchers. However, they noted that previous studies had mixed results with regards to the association between saturated fatty acids and coronary heart disease risk.

For this analysis, the researchers evaluated 73,147 women who participated in the Nurses’ Health Study from 1984 to 2012 and 42,635 men from the Health Professionals Follow-Up Study from 1986 to 2010. Both of the trials were prospective, longitudinal cohort studies.

All of the adults completed a food frequency questionnaire at baseline and during follow-up periods. They were excluded if they had cancer, diabetes or cardiovascular disease at baseline, if their total energy intake was deemed implausible or if they had missing data on individual saturated fatty acids.

Participants with higher saturated fatty acid intake at baseline were younger and more likely to be white and non-smokers. They also had lower alcohol consumption, engaged in less physical activity and had lower prevalence of hypercholesterolemia and hypertension compared with adults with lower saturated fatty acid intake.

During the study, intake of saturated fatty acids accounted for 9.0 percent to 11.3 percent of energy intake for the participants.

After adjusting for lifestyle factors and total energy intake, participants in the highest intake of lauric acid had a 7 percent increased risk of coronary heart disease compared with those in the lowest intake group. Participants in the highest intake group of myristic acid had a 13 percent increased risk of coronary heart disease, while participants in the highest intake group of palmitic acid had a 16 percent increased risk and those in the highest intake group of stearic acid had an 18 percent increased risk.

In addition, participants in the highest intake group for all four of the individual saturated fatty acids had an 18 percent increased risk of coronary heart disease compared with those in the lowest intake group.

Replacing 1 percent of the daily energy intake from the combined group of saturated fatty acids with equivalent energy from polyunsaturated fat, whole grain carbohydrates or plant proteins was associated with a 6 percent to 8 percent reduction in risk of coronary heart disease, according to the researchers.

They also cited a few limitations of the study, including that there could have been unmeasured and residual confounders. In addition, all of the participants were health professionals and had a relatively homogenous ethnicity and socioeconomic status, which could have limited the generalizability to other populations. Further, they mentioned that food frequency questionnaires might not be completely accurate and that it was difficult to measure associations of individual saturated fatty acids that were highly correlated with each other.

“Owing to high correlations among individual [saturated fatty acids] in diet, these findings support the current dietary recommendations that focus on replacement of total saturated fat as an effective approach to preventing cardiovascular disease,” the researchers wrote. “The public health and clinical significance of modulating the content of individual [saturated fatty acids] in specific foods should be further evaluated.”